As a self-employed artist and designer, I've had work ripped off in the past, and before the internet existed too. It can be a difficult issue, especially working in for what many consider a 'hobby' area. I too consider underground work a hobby, but photography and art is also my job, as I'm often paid to make photographs, or I sell images afterwards.
I'm happy to post low-res examples or watermarked larger images on the net as long as they're credited if used, However, if someone then wanted to publish those images, and were prepared to pay for them, then I would happily take their money, as this is what I do for a living, however flimsy a living it may be sometimes.
I've held back many images from the net in order to protect a commercial product before, and will do so again, no doubt. If people paid artists more for their work, we wouldn't all be so damn skint 😉